Turnbull v. Payson was a United States Supreme Court case that dealt with the issue of whether a contract between two parties was valid. The case involved a contract between the plaintiff, Turnbull, and the defendant, Payson, for the sale of a parcel of land. The contract stated that the land was to be sold for a certain amount of money, and that the payment was to be made in installments. The Supreme Court held that the contract was valid and enforceable. The Court noted that the contract was clear and unambiguous, and that the parties had agreed to the terms of the contract. The Court also noted that the contract was not unconscionable, and that the parties had the capacity to enter into the contract. The Court also held that the contract was not voidable due to the fact that the parties had not acted in bad faith. The Court noted that the parties had acted in good faith, and that the contract was not voidable due to any fraud or misrepresentation. The Court concluded that the contract was valid and enforceable, and that the plaintiff was entitled to the payment of the installments as agreed upon in the contract. The Court also noted that the defendant was not entitled to any damages for breach of contract, as the contract was valid and enforceable.

Justice Field delivered the dissenting opinion in Turnbull v. Payson, arguing that the majority had misconstrued a key provision of the contract between the parties. He argued that under Illinois law, which governed this case, an agreement to pay interest on a debt was not enforceable unless it was made in writing and signed by both parties. The majority held that such agreements were valid even if they weren't written down or signed; however Justice Field disagreed with this interpretation and believed it would lead to uncertainty and confusion among contracting parties as well as encourage fraud. He noted that while oral contracts could be enforced for certain types of transactions (such as sales), he did not believe they should be allowed when dealing with matters involving money or property interests because there is too much room for error or misunderstanding without something being put into writing. Furthermore, he argued that allowing oral agreements regarding debts would create unfairness since creditors may take advantage of borrowers who are unaware of their rights under state law - something which can only be avoided through clear documentation outlining all terms agreed upon by both sides prior to entering into any contractual arrangement.